Synthesis and characterization of CuO@Mn3O4 and NiO@Mn3O4 nanocomposites for photocatalytic and electrochemical applications
摘要
Nanocomposites (NCs) of CuO@Mn3O4 and NiO@Mn3O4 were produced via ionic precipitation method. XRD analysis confirmed crystallite sizes of 23.65 nm for CuO@Mn3O4 and 20.17 nm for NiO@Mn3O4. SEM and TEM provided detailed microstructural insights, while XPS validated the elemental composition and oxidation states of Cu2p, Ni2p, Mn2p and O1s. UV–Vis analysis revealed indirect band gap values of 1.44 eV and 1.39 eV for CuO@Mn3O4 NiO@Mn3O4 respectively. The photocatalytic performance was evaluated for Rhodamine-B (RhB) dye degradation under optimized conditions, showing that NiO@Mn3O4 achieved a high degradation % of 98.41% with a breakdown rate (kobs) of 0.06220 min⁻1, outperforming CuO@Mn3O4, which showed an 82.54% degradation with a kobs of 0.04858 min⁻1. Electrochemical CV studies revealed a specific capacitance (Csp) of 245.52 F/g for NiO@Mn3O4, surpassing CuO@Mn3O4, which exhibited 210.37 F/g at 10 mV/s. GCD analysis confirms the NiO@Mn3O4, exhibit higher Csp value of 263.17 F/g at 1 A/g, than 206.21 F/g for CuO@Mn3O4. Additionally, NiO@Mn3O4 exhibited a higher energy density (Ed = 10.8 Wh/kg) and and power density (Pd = 300.2 W/kg) compared to CuO@Mn3O4 (Ed = 259.2 Wh/kg; Pd = 5.7 W/kg). The diffusion coefficients were determined to be 2.4 × 10⁻⁷ cm2/s for NiO@Mn3O4 and 1.7 × 10⁻⁷ cm2/s for CuO@Mn3O4, while electrical conductivity (σ) was higher for NiO@Mn3O4 (4.86 × 10⁻4 S/cm) than for CuO@Mn3O4 (3.40 × 10⁻4 S/cm). This work reveals that NiO@Mn3O4 has the potential as an effective photocatalyst and electrode coating for energy storage uses.